Cutlery-grinding machine



Dec. 27, 1927. 1,654,000

A. HIRST CUTLERY GRINDING MACHINE Filed Oct. 13. 1921 2 Sheets-Sheet 1 Dec. 27, 1927. 1,654,000

A. HIRST CUTLER"! GRINDING MACHINE Filed Oct. 15. 1921 2 Sheets-Sheet 2 (Toning ltl lti

Patented Dec. 27, 1927.

UNITED STATES PATENT OFFICE.

ARTHUR itlililRSlll, U1? SHEFFIELD, ENG-LAND, ASSIGNOR 0F ON'E--lEfALF 'IO GEORGE HARRY OXLEY, 015 SHEliFIELTD, ENGLAND.

CUTLEHY-GRINDING MACHINE.

Application filed. October 13, 1921, Serial No. 507,514, and. in Great Britain October 23, 1920.

'lChis invention relates to cutlery grinding machines, its object being to provide 111iyn'oved means for enabling the complete surface of a table linife or like blade to be ground to a contour approximating to that usually ground by hand and at the some time the cutting edge to be ground a straight edge for the desired length and with such degree of sharpness as may be desired.

An ordinary table knife blade tapers both from back to cutting edge and from bolster to point, which usually rounded, the cut ting edge being straight throughout practically the whole length. The longitudinal taper is not even throughout, being most pronounced at the bacl-z and barely discern iblc at the edge; it is also more gradual at the point than at other parts of the blade, so thutthe transverse taper near the point is even pronounced than it would be if the longitudinal taper were even. liurthcr, whilst the point portions usually luive nearly a flat surface, the blade is preferably some what convex transversely near the bolster and at the middle.

lllow in cutting a recess, conforming to the tapers in such a table knife blade, whether in the circumference of a rotary blade holder, or in the surface of a plane holder, it is found that if the recess be sunk sufficiently deep at the point end for the complete blade surface to be ground. at that end, the recess will be so deep at the bolster end that the cutting edge at this end will not be sharp ened but will be of substantial thickness after both sides of the blade have been ground, although the blade may thereby be ground with a straight cutting edge. If, on the other hand the bolster end of the recess be sunl: only so deep that the cutting edge is sharpened at this end it is found. that the point end of the recess is so shallow that the boundary of the recess corresponding to the cutting edge of the blade extends from the bolster in a straight line only for a portion of its length and then merges into the sur face of the holder to join the point- (or even the back) portion of the recess in a line which resembles a spear point across the shallower end of the recess. The result of grinding a blade clamped in such a recess is that instead of grinding its complete sur face a portion of that surface will be en tirely removed and the cutting edge will. be ground to a spear point, or only the point portions of the surface will be ground.

According to the present invention a. cutlery or like blade is hold in a grinding H151 chine with its point end twisted. about a substantially longitudinal axis. 'llhe blade holder is provided with a recess for each blade to be ground, formed as described above with the bolster end sunk only so deep that the cutting edge of the blade is sharpened at this end. The recess will thus have longitiuliiuil and transverse tapers, sin'iilnr to those required in the blade, merging into the surface in a line across th e shallower end of the recess and. means are provided for holding a blade in. each recess with its point end twisted. or bent over that line. The blade holder may also be recessed on the other side of that line, preferably with opposite tapers, in order that a greater amount of twist may be imparted to the blade than. would. othcrwise be possible, this additional recessilig being specially necessary if the holder is not a cylindrical one designed to rotate. Chain nels to carry cooling fluid to the back of the blades during the grinding operation are preferably formed in the blade holder across the recesses therein.

in the accompanying drawings 1 Figure l is a radial section. through a cylindrieal blade holder of a grinding machine, recessed for the reception of a blade according to the present invention, the section. be ingtalrcn on the line .1.--1 of Figure 2, which is a plan of part of the blade holder.

Figures 3, at, and 5 are transverse sections taken respectively on the lines 3 3, ii-4t and 5--5 of Figure 2.

Figure 6 is a view similar to Figure 1 with a blade clamped in the recess ready to be ground.

Figure 7 is an elevation of the cylindrical blade holder mounted in. a suitable grinding machine.

Like reference numerals indicate like parts throughout the drawings.

A cylindrical blade holder 1 is illustrated in Figure 7. It is rotatably mounted in bearings l1 and is rotated from any suitable source of power. A grinding wheel 12 is mounted. in bearings 13 with its axis substantially pa 'allcl to that of the blade holder 1. The grinding wheel may be adjusted and fed towards the blade holder 1. by means of a handle 1d operating a screw 15. The grinding wheel 12 is preferably driven. at a com tit) siderably greater'speed than the blade holder 1, and during the grinding operation it may if desired be reciprocated' on the slide 16 in a dlirectiomparallel to its axis.

he b13216 raider 1v is provided with a series of recesses 2 around its circumference, each recess having longitudinal and transverse tapers similar to those required in the blade afterigrinding. Each of the recesses 2 is sunk only so deep at the bolster end that the cuttin edge of the blade 3 will be sharp 'ened at tis end as indicated 'in Figure 5, (the blade 3 being shown in dotted lines in "Fi ures 2,3, a, and 5-). The result will be the longitudinal and transverse tapers fof eaeh recess2 will-merge into the surface of the holder 1 in a line 4 (Figure 2) which 'crosses the shallower end of the recess. The boundary of the recess 2 corresponding to thecutt-ingedgeof the blade?) thus extends from thebolster end in a straight line 5 only or a pdrtion of its length, being continued by the line 4 'whichjoins'the boundary corresponding to the back otfthe blade at the "shallow or point'end of the recess. Preferably, h0wever,the holder 1 is recessed also on theother'side of the line 4 shown-at 6, the rcessti being "formed with tapers oppo- "site to those on the other side of the-line 4. The boundaryof the recess 6 corresponding to the cuttingedge ofthe blade is preferably formed as a. straight line extension of the corresponding part5 ofthe recess 2. It will be appreciated "that in cutting such a recess *the lime will not necessarily be sharply defined althou h there will be a slight eminence or ridge in the base'ot' the recesses 52, 6, the positio'nj'of which is approximately defined'by-the line '4.

Each (if the blades 3"is clamped in a re cess'2at the bolster end, but its point end is inivisted'about a substantially longitudinal 'ax-isso' that whilst its'ba'ck remains in the recess'2 itscuttingedge towards the point is 'broughtnearer totheholder into the re- "cessd'thu's'bendiiig theblade approximately over the line 4. The blades 3 "ma Y "be thus "halringsin knowirniann'er, whereby an elecltric' current may lee-passed through the con- *dlictor'8 whilstthe'blade holder 1"is rotated in thegrinding machine. The insulated con diictor '8 isconve'niently protectedby'a filling 9'in the groove 7 of some 'suitable'mate- "rial such as'l'ead. It is tound that with such aconstruction a current'of about two hun tired 'amperes 'at-"fifte'en volts will induce snflicient magnetic force secumly to clamp the blades 3 in the recesses 2, a'nd to twist their point ends into the recesses (i. The blades 3, thus clamped and twisted on the cylindrical revolving holder 1 are 'g'ioi'lnd iii any suitable design of grinding machine. The twistrng of the blade not only allows the cuttin edge to be ground sharp as a straight edge but also enables the complete surface of the blade to be ground to the dcsrred contour, for the convexity ground on the point portion of the blade will become preferred to form channels such as 10 across the recesses 2 and (i. the function of the channels 10 being to carry cooling fluid to the back of the blades 3 during'thegrinding process and thus to reduce the liability of the blades to bebu'rnt or over-heated by the grind-stone.

Vhen mechanical means for clamping and twisting the blades are employed the blade may be 'iorgedot extra length or with a tan-g or the like at the pointend to enable the twist to be applied. The extra length or tang would be cutol'l' after the blade had been'ground onboth sides. Or, the part of the point which is clamped. may be ground in a subsequent operation. Tt'will be appreciated that after the blades have been ground on one sidethey are transferred to a second holder with similar recesses and clamping means adapted to hold the blades for their other sides to'be ground. The recesses in the second holder would,'of course, also be shallower than the recesses in the first by the reduction in thickness of the blade'eitected in the first grinding operation.

By varying the amount of twist imparted to the blade the shape of the cutting-edge which will be ground may be altered ind by increasing itbeyond theamountrequired for astraight edge it is Epossible 'to grind and sharpen an edgewvith a concave bend.

'In'the case of a cylindrical blade holder the recess 6 may be dispensed with in some -cases,-the curvatureof the holderenabling the required twist 'to be imparted to the blades.

Having described my 'invention, what 'I clann, and (lGSIIQtO secure by Letters Patent, is

1. A cutlery grinding 'machine including The degree of sharpness imparted lot) lltl

till

means for holding a cutlery or like blade therein with its point end twisted about a substantially longitudinal axis to impart a conveig shape to its surface whilst being ground, substantially as specified.

2. In a cutlery grinding machine, the combination. of a blade holder comprising two relatively inclined supporting surfaces meeting in a ridge, means for locating a blade on one of the surfaces with the ridge extending from the back edge of the point to the cutting edge towards the tang end, and means for twisting or bending the blade into a convex shape over the ridge and for holding it thus distorted whilst being ground, substantially as specified.

3. In a cutlery grinding machine, the combination with a blade holder having a recess therein formed with a wall against which the back edge of the blade is placed to locate the cutting edge thereof and with a base to support the blade comprising two relatively inclined surfaces meeting in a ridge extending from the point supporting portion at the locating wall towards the edge supporting portion at the tang end, means for twisting or bending the blade into a convea shape over the ridge, and means for holding it thus distorted in contact with the base of the recess whilst being ground, sub etantially as specified.

l. In a cutlery grinding machine, the combination of a grinding wheel, means for rotating it, a blade holder, means for moving it repeatedly in a path adjacent to the grinding wheel, the blade holder having a recess therein formed with a wall to locate the cutting edge of a blade and with a base to support the blade comprising two relatively inclined surfaces meeting in a ridge extending from the point supporting portion at the loeating wall to the cutting edge supporting portion at the tang end, the one of said surfaces to support the tang end of the blade being inclined to the path of the blade holdor in a manner corresponding to the longitudinal and transverse tapers required in the blade and the'locating wall. of the recess being sunk to approximately half the thick ness of the blade edge, means for twisting or bending a blade in a convex shape over the ridge or the recess and means for holding it thus distorted in. contact with the base of the recess whilst being ground, substantially as specified.

5. In a cutlery grinding machine, the combination of a grinding wheel, means for rotating it, a blade holder, means for moving it repeatedly in a path EtdJElCBllil to the grinding wheel, the blade holder having a recess therein formed with awall against which the back edge of the blade is placed to locate the cutting edge of a blade and with a base to support the blade comprising two relatively inclined surfaces meeting in a ridge extending from the point supporting portion at the locating wall to the cutting edge supporting portion at the tang end, the one of said surfaces to support the tang end of the blade being inclined to the path of the blade holder in a manner corresponding to the longitudinal and transverse tapers required in the blade and the locating wall of the recess being sunk to approximately half the thickness of the blade edge, means for twisting or bending a blade into a convex shape over the ridge of the recess,

means for holding it thus distorted in contact with the base of the recess whilst being ground and a series of channels across the recess to carry cooling fluid, substantially as specified.

6. In a cutlery grinding machine, the combination of a grinding wheel, means for rotating it, a cylindrical blade holder, means for rotating it with. its periphery moving in a path adjacent to the grinding wheel, the blade holder having a series of recesses therein each formed with a wall. to locate the cutting edge of a blade and with a base to support the blade comprising two rela' tively inclined surfaces meeting in a ridge extending from the point supporting portion at the locating wall to the cutting edge sup porting portion at the tang end, the one of said surfaces to support the tang end of the blade being inclined to the path of the blade holder periphery in a manner corresponding to the longitudinal and transverse tapers required in the blade and the locating wall of the recess being sunk to approximately half the thickness of the blade edge, means for twisting or bending a blade into a convex shape over the ridge of each recess, means for holding it thus distorted in contact with the base of the recess whilst being ground, said bending and holding means comprising a spiral groove around the circumference of the blade holder crossing the series of recesses therein, an insulated electric conductor in the spiral groove, a protective lilling in the groove below the edges thereof and means for leading an electric current to the conductor, substantially as specified.

In witness whereof I have hereunto set my hand.

ARTHUR I-IIRST. 

